Climate science and the public

A Summer of Extremes

Because of our emissions of greenhouse gases like carbon dioxide, a little extra energy gets trapped in our atmosphere every day. Over time, this energy builds up. It manifests itself in the form of higher temperatures, stronger storms, larger droughts, and melting ice. Global warming, then, isn’t about temperatures as much as it is about energy.

The extra energy, and its consequences, don’t get distributed evenly around the world. Weather systems, which move heat and moisture around the planet, aren’t very fair: they tend to bully some places more than others. These days, it’s almost as if the weather picks geographical targets each season to bombard with extremes, then moves on to somewhere else. This season, the main target seems to be North America.

The warmest 12 months on record for the United States recently wrapped up with a continent-wide heat wave and drought. Thousands of temperature records were broken, placing millions of citizens in danger. By the end of June, 56% of the country was experiencing at least “moderate” drought levels – the largest drought since 1956. Wildfires took over Colorado, and extreme wind storms on the East Coast knocked out power lines and communication systems for a week. Conditions have been similar throughout much of Canada, although its climate and weather reporting systems are less accessible.

Does that mean that these particular events were caused by climate change? There’s no way of knowing. It could have just been a coincidence, but the extra energy global warming adds to our planet certainly made them more likely. Even without climate change, temperature records get broken all the time.

However, in an unchanging climate, there would be roughly the same amount of record highs as record lows. In a country like the United States, where temperature records are well catalogued and publicly available, it’s easy to see that this isn’t the case. From 2000-2009, there were twice as many record highs as record lows, and so far this year, there have been ten times as many:

The signal of climate change on extreme weather is slowly, but surely, emerging. For those who found this summer uncomfortable, the message from the skies is clear: Get used to it. This is only the beginning.

I hope we do have a mild year or three, but it is slowly looking less likely. As you probably know, the decades between the 1950s and today, beginning with the 1980s, have shown a sharp increase in the ratio of new highs to new lows, and the trend appears to be accelerating. At the same time, there is “Watts’s Law”: “Every new weather extreme signals the beginning of a recovery from that extreme.” See “The Double Recovery of Arctic Sea Ice” at http://denialdepot.blogspot.com/2012/06/double-recovery-of-arctic-sea-ice.html .

As climatehawk1 says, here in the UK we have had the wettest three months (Apr-June) and the wettest June on record. In July, the NW of Scotland has had 10% of the LTA rainfall whereas SE England has had over 300% (yes 3 times) the LTA rainfall.

Given the fact that the Arab Spring of 2011 was triggered by a spike in food prices following the failure of Russian harvests in 2010, I think the scariest thing is that – whether it be droughts, frosts or floods – the consequence of ACD is the same will be the same; higher food prices.

Sadly, all of this was predicted long ago by the MIT’s Limits to Growth reports in 1972, 1992, and 2005.

That highs vs lows math doesn’t work when you have a temperature record that goes back to a point that was substantially lower. You will of course have more high records than low records, even if there is no ongoing global warming happening right now, simply because it is warmer now than before.

The United Kingdom has indeed had to endure a dismal period, which has been very detrimental to wildlife, as well as humans. In the future, government policy will have to cover all manner of things, including better management of our ecosystems. This potentially being a law set in stone for a generation at a time, say 100 years. Take the unusual weather pattern of June 2012 as a prime example of what COULD become the norm.

About

Kaitlin Alexander is a PhD student in climate science at the University of New South Wales in Sydney, Australia. She became interested in climate science as a teenager on the Canadian Prairies, and increasingly began to notice the discrepancies between scientific and public knowledge on climate change. She started writing this blog at age sixteen to help address this gap in public understanding, and it slowly evolved into a record of her research as a young climate scientist. Read more

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